The usefulness of a three-protein signature blood assay (Mastocheck®) for follow-up after breast cancer surgery

PURPOSE: Mastocheck®, a proteomic-based blood assay, has been developed for early diagnosis of breast cancer. The purpose of this study is whether Mastocheck® is useful as a postoperative follow-up. METHODS: A total of 255 patients were analyzed. The patients were classified into longitudinal monitoring and recurrence/nonrecurrence cohorts. The longitudinal monitoring cohort consisted of 111 patients. In this cohort, blood analyses were performed three times (before surgery, 8 weeks after surgery, and between 6 months and one year after surgery), and a comparative analysis of the values of Mastocheck® and individual proteins at each time point was performed. The recurrence/nonrecurrence cohort consisted of 144 patients who had been followed up for more than 1 year, and the blood marker values at the time of local recurrence were compared to those of nonrecurrence patients. RESULTS: In the longitudinal monitoring cohort analysis, in 81 of 111 patients were diagnosed with breast cancer with Mastocheck® and the sensitivity was 73.0%. Of 111 patients in the longitudinal monitoring cohort, 108 had two blood analyses (before and 8 weeks after surgery), and three serial blood analyses were performed on 53 patients. The Mastocheck® value that were in the cancer range of 73.0% (in 81 of 111 patients) of patients before surgery, was within the normal range of 68.5% (in 74 of 108 patients) at 8 weeks after surgery and 88.7% (in 47 of 53 patients) from 6 months to 1 year after surgery. The value of Mastocheck® was significantly decreased after surgery compared to before surgery (p < 0.001). In the recurrence/nonrecurrence cohort analysis, the Mastocheck® values were in the cancer range in 38 out of 63 recurrence patients and within the normal range in 66 of 81 nonrecurrence patients (sensitivity of 60.3% and specificity of 80.2%). CONCLUSIONS: Mastocheck® is expected to be used as a blood marker tool to aid in the early detection of recurrence during follow-up after breast cancer surgery.